Plastisol composition and undercoating material

ABSTRACT

A plastisol composition comprising a vinyl chloride polymer, a plasticizer and an adhesion-imparting agent, characterized in that the adhesion-imparting agent is a diisocyanate polymer blocked with an oxybenzoic acid ester or with an alkylphenol and having an average molecular weight within a range of from 1,000 to 10,000.

This is a continuation, of U.S. application Ser. No. 06/895,813, filedAug. 12, 1986 now abandoned.

The present invention relates to a plastisol composition most suitablefor applications for bonding or coating, and an undercoating materialcomposed of such a plastisol useful as a sealer or undercoating materialfor automobile industries and various other industries.

A coating (top coating) is applied to automobiles and various industrialproducts. Prior to the application of this coating, it is common toapply a pre-treatment coating commonly called an undercoating for thepurpose of sealing, protection of the substrate or facilitating thesurface finish. Such an undercoating is essential particularly to anautomobile body to which a cation-type electrodeposition precoating isapplied. A polyvinyl chloride plastisol composition as an undercoatingmaterial for such an undercoating is not yet widely used because itsadhesion is not adequate.

As a method for improving the adhesion of the plastisol, it is known toincorporate an organic polyisocyanate compound to the plastisol. Forinstance, it is disclosed to add to the plastisol an isocyanate polymerobtained by trimerizing tolylene diisocyanate (TDI) in UK Patent No.1,455,701 or an isocyanate polymer of isocyanate-isocyanurate obtainedby partially trimerizing a two component mixture comprising TDI anddiphenylmethane diisocyanate (MDI). These isocyanate polymers have freeisocyanate groups (NCO) at their terminals, and they are extremelyreactive and thus inferior in the storage stability of the plastisol, inthe operation efficiency such as non-uniformity in the application ofthe plastisol to the substrate or formation of air bubbles, and in thequality stability.

Namely, when a plastisol is prepared by mixing an isocyanate polymerhaving terminal NCO groups in an inert solvent e.g. a plasticizer, therehave been problems such as (1) a substantial decrease in the adhesionstrength, (2) gradual viscosity increase or solidification as timepasses and (3) formation of air bubbles, by the influence of a smallamount of moisture or a metal catalyst remaining in the plasticizer.

Therefore, with respect to the metal component, it has been required tolimit the amount to the minimum and there has been a problem that if theamount is too small, the formed sheet undergoes substantial coloring.Therefore, the application has been limited to a very restricted blendsystem, and there have been various drawbacks such that the processingand operation process are restricted.

In recent years, there have been proposed a method wherein an activeamino group-containing mono- or poly-amide compound is added, as anagent for promoting the dissociation of a blocked polymer (hereinafterreferred to simply as a "block dissociation-promoting agent") to aplastisol of a urethane polymer containing an oxime as a blocking agent(Japanese Examined Patent Publication No. 52901/1984); a method whereina compound selected from the group consisting of nitrogen-containingpolyols, amino-alcohols and fatty acid alkanol amides, is added, as ablock dissociation-promoting agent, to a urethane prepolymer containingan oxime or lactam as a blocking agent (Japanese Unexamined PatentPublication No. 78279/1984); a method wherein a mono- or poly-carboxylicacid is further added to the above-mentioned composition of JapaneseExamined Patent Publication No. 52901/1984 and Japanese UnexaminedPatent Publication No. 120651/1984; and a method wherein an alkyleneoxide-added polyol is added to a lactam-blocked polyisocyanate, anactive amino group-containing polyamide and a low molecular weight amine(Japanese Unexamined Patent Publication No. 131669/1984).

However, in the above references, (a) the method wherein an active aminogroup-containing mono- or poly-amide is used as a blockdissociation-promoting agent, has drawbacks such thatdehydrochlorination from the polyvinyl chloride is promoted, and theproduct tends to undergo a color change by heat and is inferior in thecolor fastness to light and in the water resistance; (b) thepolyisocyanate contains urethane linkages of a polyol and an aliphaticor aromatic isocyanate, whereby there is a problem of the formation ofair bubbles during the processing, and the product is not satisfactoryas to the water resistance and weather resistance for a long run; and(c) the blocking agent is an oxime or a lactam, whereby thecompatibility with the resin component after dissociation or with aplasticizer is inferior, thus leading to blooming or bleeding, and whencontacted with an acid, the oxime undergoes hydrolysis, and the lactamforms a crystalline salt, such being problematic. Thus, they are likelyto impair the stability, such as the heat resistance or the waterresistance, of the shaped product.

The present inventors have conducted extensive researches to overcomethe conventional difficulties and to develop a plastisol compositionwhich can be used in combination with various additives, which is freefrom the deterioration of the properties even in a high temperature,high humidity atmosphere, which does not undergo a color change or theformation of air bubbles, which can be processed in a stabilized state,and yet which is capable of providing a high adhesive strength. As aresult, it has been found possible to achieve the above object by addinga certain specific blocked diisocyanate polymer to the plastisol, as anadhesion-imparting agent. The present invention has been accomplished onthe basis of this discovery.

Namely, it is an object of the present invention to provide a plastisolcomposition which is capable of being processed under various conditionssuch as high temperature and high humidity conditions without a colorchange, formation of air bubbles or a deterioration of the adhesivestrength.

Another object of the present invention is to provide an undercoatingmaterial composed essentially of such a plastisol composition containingan adhesion-imparting agent having good storage stability and beingcapable of firmly bonding to a electro-deposited metal in a short periodof time within a wide temperature range from a relatively lowtemperature to a high temperature.

The present invention provides a plastisol composition comprising avinyl chloride polymer, a plasticizer and an adhesion-imparting agent,characterized in that the adhesion-imparting agent is a diisocyanatepolymer blocked with an oxybenzoic acid ester or with an alkylphenol andhaving an average molecular weight within a range of from 1,000 to10,000.

Further, the present invention provides an undercoating materialcomposed of a plastisol composition comprising a vinyl chloride polymerand a plasticizer as main components, wherein the plastisol compositioncontains a diisocyanate polymer blocked with an oxybenzoic acid ester orwith an alkylphenol, as an adhesion-imparting agent.

Now, the present invention will be described in detail with reference tothe preferred embodiments.

The vinyl chloride polymer as the main component of the plastisolcomposition of the present invention, is a paste resin having an averageparticle size of at most 5 μm, preferably from 0.05 to 3 μm, prepared bythe emulsion polymerization of vinyl chloride or a mixture of vinylchloride with a comonomer copolymerizable therewith, in the presence ofan emulsifier and an aqueous polymerization initiator, or a paste resinor a resin to be blended with a paste resin prepared by microsuspensionpolymerization which comprises mechanically finely dispersing a part orentire amount of vinyl chloride or a mixture of vinyl chloride with acomonomer copolymerizable therewith, in the presence of a dispersant andan oil-soluble polymerization initiator, followed by polymerization.Further, a vinyl chloride resin or a vinyl chloride copolymer resinhaving a large particle size produced by a usual suspensionpolymerization may be incorporated in an amount not to adversely affectthe viscosity, fluidity, processability, etc. of the plastisol ororganosol. As the comonomer copolymerizable with vinyl chloride, theremay be mentioned a vinyl ester such as vinyl acetate, vinyl propionateor vinyl laurate; an acrylate such as methyl acrylate, ethyl acrylate orbutyl acrylate; a methacrylate such as methyl methacrylate or ethylmethacrylate; a maleate such as dibutyl maleate or diethyl maleate; afumarate such as dibutyl fumarate or diethyl fumarate; a vinyl ethersuch as vinyl methyl ether, vinyl butyl ether or vinyl octyl ether; anitrile such as acrylonitrile or methacrylonitrile; an α-olefin such asethylene, propylene or styrene; a vinylidene halide or vinyl halideother than vinyl chloride, such as vinylidene chloride or vinyl bromide;and N-methylol acrylamide. At least one of these comonomers may beemployed in an amount of not more than 30% by weight, preferably notmore than 20% by weight.

For the polymerization of a vinyl chloride polymer, it is common to usean emulsifier containing an alkali metal salt. However, in view of theadhesive properties of the composition of the present invention, it isdesirable in the present invention to select an emulsifier so that thealkali metal content in the vinyl chloride polymer will be not higherthan 900 ppm. As an emulsifier which brings about such a low alkalimetal content in the vinyl chloride polymer, an ammonium salt or analkali metal salt of an fatty acid having an alkyl group with from 8 to18 carbon atoms may be mentioned as an example. However, the emulsifieris not restricted to such a specific example.

There is no particular restriction as to the plasticizer to be used as acomponent of the plastisol composition of the present invention, and anyplasticizer may be employed so long as it is suitable for use for avinyl chloride polymer. For instance, there may be mentioned a phthalateplasticizer such as di-n-butyl phthalate, di-n-octyl phthalate,di-2-ethylhexyl phthalate (DOP), diisooctyl phthalate, octyldecylphthalate, diisodecyl phthalate, butylbenzyl phthalate, di-2-ethylhexylisophthalate or a mixed alkyl phthalate; a fatty acid ester plasticizersuch as di-2-ethylhexyl adipate (DOA), di-n-decyl adipate, diisodecyladipate, di-2-ethylhexyl azelate, dibutyl cebacate or di-2-ethylhexylcebacate; a phosphate plasticizer such as tributyl phosphate,tri-2-ethylhexyl phosphate, 2-ethylhexyldiphenyl phosphate or tricresylphosphate; and an epoxy plasticizer such as epoxidized soybean oil orepoxidized tall oil fatty acid-2-ethylhexyl. These plasticizers may beused alone or in combination as a mixture of two or more differentkinds. The amount of the plasticizer to be used is properly selecteddepending upon the desired solid content or the fluidity of the pastesol, and is usually within a range of from 30 to 600 parts by weight,preferably from 50 to 200 parts by weight, relative to 100 parts byweight of the vinyl chloride resin.

Further, a part of the plasticizer may be substituted by a diluent suchas hexanol isobutyrate or dodecylbenzene or by an organic solventcapable of permitting the vinyl chloride resin to swell such as tolueneor xylene, to form an organosol. The amount of the diluent or theorganic solvent is properly determined depending upon the particularuse.

The plastisol composition of the present invention contains adiisocyanate polymer blocked with an oxybenzoic acid ester or analkylphenol as its one component. The blocked diisocyanate polymerpreferably has an average molecular weight within a range of from 1,000to 10,000. If the average molecular weight of the blocked polymer isless than 1,000, no adequate adhesion is obtainable, and the adhesivestrength will be inadequate. On the other hand, if the average molecularweight is greater than 10,000, the viscosity of the sol compositiontends to be extremely high. As the diisocyanate (monomer) constitutingthe isocyanate polymer, there may be mentioned an fatty aciddiisocyanate such as hexamethylene diisocyanate or lysine diisocyanate;an alicyclic diisocyanate such as hydrogenated diphenylmethanediisocyanate, isophorone diisocyanate or hydrogenated tolylenediisocyanate; and an aromatic diisocyanate such as tolylenediisocyanate, diphenylmethane diisocyanate, naphthylene diisocyanate orxylene diisocyanate. Among them, the aromatic diisocyanate, particularlytolylene diisocyanate or diphenylmethane diisocyanate is especiallypreferred. Then, the diisocyanate polymer can be obtained by thepolymerization in accordance with a conventional method in an inertsolvent such as ethyl acetate, methyl acetate, butyl acetate, methylethyl ketone or dioxane, or in a plasticizer such as a phthalate, aphosphate, an adipate or a trimellitate by using a well known catalystsuch as a tertiary amine, a Mannich base, an alkali metal salt of afatty acid or an alcoholate. The isocyanate polymer is then subjected toa blocking reaction with an oxybenzoic acid ester or with an alkylphenol, to obtain a blocked diisocyanate polymer. When thepolymerization reaction or the blocking reaction is conducted in ahighly volatile solvent, it is preferred to finally substitute thesolvent by a proper high boiling point solvent such as a plasticizer.

It is particularly preferred to employ a diisocyanate polymer obtainedby the polymerization of a diisocyanate monomer and containingisocyanurate rings, as the diisocyanate polymer to be used in thepresent invention. The polymer containing isocyanurate rings may beprepared in accordance with the above-mentioned method. It is of coursepossible to employ as the isocyanate polymer, a polyurethane or polyureahaving so-called isocyanate terminal groups, obtained by the reaction ofdiisocyanate with an active hydrogen compound.

The oxybenzoic acid ester to be used as the blocking agent, includes ano-oxybenzoic acid ester, a m-oxybenzoic acid ester or a p-oxybenzoicacid ester. Among them, particularly preferred is a p-substituted ester.

The other group constituting the oxybenzoic acid ester is preferably along chain alkyl group such as a n-hepthyl group, a n-octyl group, a2-ethylhexyl group, a nonyl group or a dodecyl group; an alkoxyalkylgroup having a long chain polyoxyethylene or polyoxypropylene groupbonded thereto, or an alkoxy alkyl group having a long chain alkyl groupwith an oxyethylene or oxypropylene group bonded thereto, in the case ofm- and p-substituted esters. In the case of o-substituted esters, analkyl group such as a methyl group, an ethyl group, an isopropyl group,an isoamyl group, a n-butyl group, an isobutyl group, a sec-butyl group,a n-heptyl group, a n-octyl group, a 2-ethylhexyl group, a nonyl groupor a dodecyl group; an alkoxyalkyl group having a (poly)oxyethylene or(poly)oxypropylene group bonded thereto; or an aryl group such as aphenyl group or a benzyl group, may be mentioned.

The alkylphenol used as a blocking agent is a phenol having, as asubstituent, an alkyl group having at least 4 carbon atoms. Forinstance, butylphenol, hexylphenol, octylphenol or nonylphenol may bementioned. Of course, the useful alkylphenol is not restricted to thesespecific examples.

The blocking agent is used usually in an amount about stoichiometic tofree isocyanate groups of the diisocyanate polymer.

The amount of the blocked diisocyanate polymer is usually within a rangeof from 1 to 25 parts by weight, preferably from 2 to 17 parts byweight, per 100 parts by weight of the vinyl chloride polymer, so thatthe effective NCO content in the plastisol composition is usually withina range of from 0.03 to 1% by weight, preferably from 0.03 to 0.6% byweight, more preferably from 0.05 to 0.5% by weight. For instance, whena dibutyl phthalate solution containing 33% by weight of a diisocyanatepolymer blocked with an oxybenzoic acid ester prepared by thepolymerization and blocking in dibutyl phthalate, is to be used, thesolution is employed in an amount of from 2 to 50 parts by weight per100 parts by weight of the vinyl chloride polymer. If the amount of theplasticizer is inadequate, the plasticizer is supplemented to obtain aplastisol composition. Likewise, since the effective NCO content in the33% dibutyl phthalate solution may vary, the diluent is properlyadjusted to bring the NCO content in the plastisol composition to adesired level. If the NCO content is less than 0.03% by weight, theeffects for adhesion tends to be poor. On the other hand, if the contentexceeds 1% by weight, undesirable phenomena such as an increase of theviscosity and coloring of the sol, are likely to occur, and abubble-forming phenomenon due to absorption of moisture and vigorousreaction is observed at the bonding interface, whereby the adhesivestrength tends to deteriorate.

The plastisol composition of the present invention preferably containsan agent for promoting the dissociation of the blocked structure of theoxybenzoic acid ester- or alkylphenol-blocked diisocyanate polymer. Assuch a block dissociation-promoting agent, an inorganic or organiccompound of an alkali metal and an inorganic or organic compound of ametal such as lead, tin, cadmium or zinc, may be mentioned. It isdesirable to use at least one of these compounds.

As the alkali metal compound, a potassium or sodium salt or apotassium-zinc or sodium-zinc composite stabilizer of a fatty acid,particularly a fatty acid having an alkyl group with from 8 to 18 carbonatoms, an alkylsulfuric acid, an alkylarylsulfonic acid, analkylsulfonic acid or a polyoxy ethylene adduct thereof may bementioned. The metal compound other than the alkali metal compound,includes an inorganic metal compound such as white lead, basic leadsilicate, tribasic lead sulfate, tribasic lead phosphite, silica gelco-precipitated lead silicate or zinc white, and an organic compoundsuch as a metal salt, e.g. a cadmium, barium, calcium, zinc, lead, tinor magnesium salt, of lauric acid, stearic acid, ricinolic acid,naphthenic acid, salicyclic acid, 2-ethylhexoinic acid fatty acid orresin acid, and it also includes zinc octylate, dibutyltin laurate,dioctyltin maleate and dibutyltin mercaptide. Further, it is posssibleto employ organic acid liquid composite stabilizers of e.g.calcium-zinc, barium-zinc, magnesium-zinc, cadmium-barium-zinc types,which are commercially available usually as stabilizers for vinylchloride resins. Among them, lead-type or tin-type compounds areparticularly preferred.

With respect to the amount of the block dissociation-promoting agent,the alkali metal compound may be incorporated in the plastisolcomposition preferably in an amount of not higher than 900 ppm as thealkali metal relative to the vinyl chloride polymer. In a case where analkali metal is already contained in an emulsifier used for thepreparation of the vinyl chloride polymer, such an amount is taken intoaccount as the alkali metal amount for the calculation of the content ofthe alkali metal, so that a proper amount of the alkali metal compoundas the block dissociation-promoting agent may be added. If the alkalimetal content exceeds 900 ppm, the hygroscopic properties of theplastisol during or after its preparation tend to increase, whereby thestability of the plastisol viscosity and the adhesion reaction will besubstantially impaired and the processability tends to deteriorate, andthe adhesion strength is likely to deteriorate. When the metal compoundsother than the alkali metal compounds are used as the blockdissociation-promoting agents, there is no particular restriction as tothe amount used, as they serve also as stabilizers. However, it iscommon to use them in an amount of from 0.5 to 10 parts by weight,preferably from 1 to 5 parts by weight, per 100 parts by weight of thevinyl chloride polymer, to attain the object. Further, the adhesionstrength can be synergistically improved by using the alkali metalcompound together with the compound of a metal such as lead, tin,cadmium or zinc.

For the preparation of the plastisol composition of the presentinvention, the vinyl chloride polymer, the plasticizer and theadhesion-imparting agent, are uniformly mixed, if necessary, togetherwith the block dissociation-promoting agent and other additives.

In the present invention, it is preferred (1) to use a vinyl chloridepolymer which has been stored in a completely sealed state immediatelyafter its preparation, (2) to apply a vacuum defoaming step during theplastisol preparation prior to the addition of the adhesion-impartingagent, and (3) to conduct, after the addition of the adhesion-impartingagent, the stirring and mixing with the gas phase either vacuumed fordefoaming or substituted by an inert gas such as nitrogen.

During the preparation of the composition, the entrance of moisture intothe composition should be avoided as far as possible. More specifically,it is desirable that the preparation is conducted in an atmospherehaving a relative humidity of not higher than 80%. In general, if themixing is conducted in an atmosphere having a relative humidity ofhigher than 80%, a very small amount of moisture at a level of at least0.2% by weight will be absorbed in the plastisol.

The plastisol composition of the present invention may be used as anadhesive, as a rust preventive or as a laminating agent, for nylonfibers or woven fabrics, polyester fibers or woven fabrics, or forsheet-form substrates such as sheets or films of a natural leather or asynthetic resin such as nylon or polyester, or for cationicelectrodeposition coated plates. The application to the sheet-formsubstrates may be conducted by various means such as a reverse rollmethod, a knife coater method, a spray method, a curtain flow method, adip coating method, a rotary screen method, a flat screen method, aflexor method or a gravure printing method.

The sheet-form substrate coated with the plastisol composition, isheated to a temperature of from 120° to 210° C. to dissociate the blockpolymer to form a vinyl chloride resin coating layer firmly on thesheet-form substrate. Otherwise, after the sheet-form substrate coatedwith the plastisol composition, was heated to a temperature lower thanthe dissociation temperature of the block polymer structure and theplastisol composition was melted, cooled and solidified, a separatewoven fabric, sheet or film is laid thereon and press-bonded underheating at a temperature higher than the dissociation temperature of theblocked polymer, to obtain a laminated sheet.

The plastisol composition of the present invention can be preparedwithout losing the adhesive properties even in a high temperature andhigh humidity atmosphere, and has the stability in the sol viscosity andthe adhesion strength remarkably improved over the conventional adhesivesol compositions.

In the case where the adhesion-imparting agent is an oxybenzoic acidester-blocked diisocyanate polymer, it is possible to obtain a laminatehaving high adhesion strength even by lamination at a low temperature ofabout 160° C. In this case, the blocking agent undergoes dissociation ata relatively low temperature of from 120° to 160° C. to provideexcellent adhesion.

In the case where the adhesion-imparting agent is a long chain alkylphenol-blocked diisocyanate polymer, the dissociation of the blockingagent does not proceed at a low temperature of up to 130° C., andvarious or complicated treating methods may be employed, for instance,the composition once treated for gelation at a low temperature can beagain used for lamination.

Since the adhesion-imparting agent contained in the plastisolcomposition is a diisocyanate polymer blocked with an oxybenzoic acidester or with a long chain alkyl phenol, and no amine-type blockdissociation-promoting agent is contained, there will be no formation ofair bubbles, no coloring or no decomposition of the vinyl chloridepolymer during the processing, and the adhesion strength will beremarkably high. Further, in the composition, the dissociation of theblocking agent does not proceed, even when heated to a temperature nothigher than about 100° C., and thus the composition has good stabilityin the sol viscosity and good storage stability.

For the undercoating material of the present invention, it is preferredto employ, as a combination which satisfies the low temperature meltingproperties, the adhesive properties and the storage stability, a mixturecomprising, as a vinyl chloride polymer, a paste resin composed of ahomopolymer of vinyl chloride having an average degree of polymerizationof at most 1600, and a resin to be blended with the paste resin (i.e. ablending resin) composed of a vinyl chloride-vinyl acetate copolymerhaving an average particle size of from 10 to 50 μm and having a vinylacetate content of from 1 to 10% by weight. The amount of the blendingresin to be incorporated, is usually preferably within a range of from 5to 50% by weight based on the total vinyl chloride polymer.

To the undercoating material of the present invention, various additivesother than the above components, such as a filler, a thickener, acoloring agent and the like may be incorporated. Of course, otheradditives are not restricted to such specific examples. The fillerincludes an inorganic filler such as precipitated or ground calciumcarbonate, talc, diatomaceous earth, kaolin or barium sulfate, and anorganic filler such as cellulose powder, rubber powder or regeneratedrubber. The thickener includes anhydrous silica, organic bentonite or ametal soap. When the plastisol composition contains moisture, a smallamount of a powder such as calcium oxide, magnesium oxide or siliconoxide, may be added as a moisture absorber.

The undercoating material of the present invention may be applied tovarious industrial purposes as a coating material for primer coating orfor pretreatment of the substrate surface. Particularly, in theautomobile industry, it is particularly useful as a primer coatingmaterial for a top coating synthetic resin coating material such as analkyd resin coating material, an epoxy resin coating material or anacrylic resin coating material, as applied on an automobile body towhich a cationic electrodeposition coating has been applied, for thepurpose of the prevention of rusts, or for the purpose of damping theshock when hit by an object such as a small stone, or for the purpose ofsealing pin holes or the like.

The above-mentioned cationic electrodeposition coating may be conductedin such a manner that a coating material such as an aqueous solution oraqueous dispersion prepared by neutralizing e.g. a polyamide resin (e.g.an epoxy resin having amino groups in the molecule) with a lower organicacid, is deposited on the surface of the object to be coated (automobilebody) by conducting a direct current by using the object (automobilebody) as the cathode.

The undercoating material of the present invention may be appliedusually in a coating amount of from 500 to 3000 g/m². The thickness ofthe coating layer may be adjusted within a wide range of from 0.3 to 2mm. Of course, the coating amount and the thickness are not restrictedto the above ranges, and may be adjusted to any desired levels. Theundercoating material may be applied by any conventional method. Forinstance, spray coating, brush coating, dipping and spreading are maincoating methods. As other means, the coating may be made by usingvarious equipments such as a reverse rolls, a knife coater, a rotaryscreen, a flat screen, a flexor or a gravure printer. The undercoatingmaterial coated on the object, is then heated usually to a temperatureof from 120° to 210° C. to dissociate the block polymer to form acoating layer on the surface of the object.

The heat treatment after the coating in the present invention ispreferably conducted at a temperature within a range of from 120° to150° C. for from 20 to 40 minutes by using a blockdissociation-promoting agent, whereby a coating layer having goodproperties will be obtained.

The undercoating material of the present invention contains adiisocyanate polymer blocked with an oxybenzoic acid ester or with analkylphenol, as an adhesion-imparting agent in the plastisolcomposition, and is capable of being firmly bonded to a metal surface orto a cation electrodeposition coated surface by heat treatment at arelatively low temperature in a short period of time. The plastisolcomposition constituting the undercoating material has good storagestability, whereby no substantial increase in the viscosity is observedeven when left for a long period of time, and the coating operation tothe object is simple. Further, even when the blocking agent isdissociated from the diissocynate polymer, there will be no substantialbleeding or blooming phenomena since the compatibility with theplasticizer and/or the vinyl chloride polymer is good. Further, theundercoating material of the present invention does not contain anamine-type block dissociation-promoting agent, there will be no coloringor no substantial decomposition of the vinyl chloride polymer during orafter the coating operation. Therefore, there will be no problem ofcolor change even when the top coating layer is relatively thin. Thecoating layer obtained by the undercoating material of the presentinvention has various advantages such as excellent water resistance.

Now, the present invention will be described in further detail withreference to Examples. However, it should be understood that the presentinvention is by no means restricted to these specific Examples.

The methods for the evaluation of plastisol compositions in thefollowing Examples, are as follows:

(1) Quantitative analysis of an alkali metal

The amount of the alkali metal was determined by an atomic-absorptionspectroscopy.

Namely, 10 g of a sample such as a vinyl chloride polymer or a blockdissociation-promoting agent, was stirred in 300 ml of distilled waterfor 8 hours, and then filtered with a filter paper (5A, manufactured byToyo Kagaku Sangyo K. K.). The filtrate was further filtered through amillipore filter of 0.22 μm. The filterate was analyzed by an atomicspectroscopy (by using Joulel Ash AA 8200 analyzer, manufactured byYANACO). The metal content was quantitatively analyzed based on thevalues of an external calibration chart preliminarily obtained.

(2) Measurement of the plastisol viscosity

The plastisol viscosity at 5 rpm was measured at a plastisol temperatureof 23° C. by means of B8H Model viscometer manufactured by Tokyo KeikiK. K. For the measurement of the plastisol viscosity as time passes, theplastisol was stirred gently for one minute with a stirring rod twohours before the measurement.

(3) Peel strength

A plastisol composition was coated on a polyethylene terephthalate wovenfabric of 335 g/m² or on a polyethylene terephthalate film having athickness of 90 μm by a knife coater in a thickness of 0.8 mm or 0.1 mm,respectively, and then heated for five minutes at a temperature of 160°C., 175° C. or 190° C. in a hot air circulation-type dryer to obtain alaminate wherein a vinyl chloride resin was laminated on thepolyethylene terephthalate woven fabric or the polyethyleneterephthalate film. The laminate was left for three days in a constanttemperature room, and then cut into test pieces having a width of 2.54cm and a length of 8 cm. From one end of each test piece, the coatinglayer was peeled in the direction of the length at a pulling speed of 50mm/min by 180° T-type peeling test to determine the adhesion strength tothe polyethylene terephthalate woven fabric or to the polyethyleneterephthalate film. The peel strength was represented by an average peelstrength (unit: kg/inch) of five test pieces.

(4) Evaluation of the coloring and the formation of air bubbles

The formation of air bubbles and the coloring state in the vinylchloride polymer layer of the laminate prepared for the peel strengthtest, were examined by visual observation and evaluated in accordancewith the following standards.

: None

Δ: Some

χ: Substantial

EXAMPLE 1 and COMPARATIVE EXAMPLES 1 to 3

    ______________________________________                                        Vinyl chloride polymer (paste resin,                                                                 100 parts by weight                                    alkali metal content: 770 ppm)                                                Plasticizer (di-2-ethylhexyl phthalate DOP)                                                           60 parts by weight                                    Epoxy stabilizer (FEP-13, tradename,                                                                  3 parts by weight                                     manufactured by Adeka Argus K.K.)                                             Ba--Zn type stabilizer and block dissoci-                                                             3 parts by weight                                     ation-promoting agent (AC-303, tradename,                                     manufactured by Adeka Argus K.K.)                                             CaO                     1.5 parts by weight                                   Adhesion-imparting agent                                                                             Various amounts                                        ______________________________________                                    

The above identified components were left to stand for a few days in aconstant temperature and humidity chamber at a temperature of 23° C.under a relative humidity of 50%, then weighed and mixed in a constanttemperature room in the following manner.

The paste resin, DOP (corresponding to 45 phr), the stabilizer and blockdissociation-promoting agent, were introduced into a Hobart mixer, anduniformly mixed and kneaded, and then a predetermined amount of adibutyl phthalate (DBP) solution of the adhesion-imparting agent wasadded thereto. Further, DOP was added to bring the amount to 60 parts byweight, and the composition was uniformly mixed, and then vacuumed fordefoaming to obtain a plastisol composition.

The details of the composition, the plastisol viscosity, the peelstrength (adhesive strength to the polyethylene terephthalate wovenfabric), the formation of air bubbles and the coloring, were as shown inTable 1.

For the purpose of comparison, tests were conducted in the same manneras the above Example with respect to a composition wherein noadhesion-imparting agent was added, a composition wherein a non-blockedTDI polymer was used and a composition wherein a commercially availablepolyisocyanate was used.

                                      TABLE 1                                     __________________________________________________________________________                               Comparative                                                                            Comparative                                                                             Comparative                                     Example 1  Example 1                                                                              Example 2 Example 3                       __________________________________________________________________________    Plastisol composition                                                         Adhesion-imparting agent                                                                      TDI polymer blocked                                                                      No addition                                                                            TDI polymer (not                                                                        Polyisocyanate/                                 with nonyl phenol   blocked)  polyamide*                      Average molecular weight                                                                      1182       --       522       --                              Solution concentration (wt. %)                                                                 32        --        25       30                              Effective NCO content (wt. %)                                                                 2.54       --       3.8       4.0                             in the solution                                                               Amount of the solution added                                                                   10        --        10       6.3/2.0                         (phr)                                                                         Effective NCO content (wt. %)                                                                 0.14       0        0.22      0.14                            in the sol                                                                    Plastisol viscosity (cps)                                                     Initial         4,000      3,200    4,800     2,000                           1 day later     4,000      4,400    Not measurable due                                                                      2,200                                                               to solidification                         4 days later    4,600      4,600    Not measurable due                                                                      3,000                                                               to solidification                         7 days later    4,800      4,800    Not measurable due                                                                      3,600                                                               to solidification                         30 days later   8,000      7,200    Not measurable due                                                                      --                                                                  to solidification                         Physical properties of the                                                    laminate product                                                              Heating temperature (°C.)                                                               160                                                                              175                                                                              190 160                                                                              175                                                                              190                                                                              160                                                                              175 190                                                                              160                                                                              175                                                                              190                       Peel strength (kg/inch)                                                                        3.3                                                                              5.5                                                                              8.1 1.0                                                                              1.5                                                                              2.0                                                                              4.2                                                                              5.6 8.3                                                                              -- 1.8                                                                              --                        Formation of air bubbles                   Δ                                                                          --    --                        Coloring               Δ         Δ                                                                           X  -- X  --                        __________________________________________________________________________     *Commercially Available Polyisocyanate: A TDIethylene glycol adduct           blocked with ε-caprolactam.                                            Commercially Available Polyamide: A polyamide having active amino groups     amine value: 236.                                                        

In the case of the TDI polymer in Comparative Example 2, the plastisolviscosity stability is extremely poor, and the composition underwentgelation and solidification as soon as one day later, whereby it wasimpossible to measure the viscosity.

In the case of the polyisocyanate/polyamide type adhesion-impartingagent in Comparative Example 3, the coloring was substantial, and thepeel strength was low.

In the case of the plastisol composition of the present invention, theplastisol viscosity stability was substantially equal to the compositionof Comparative Example 1, and yet a remarkable improvement in the peelstrength was observed.

EXAMPLES 2 and 3 and COMPARATIVE EXAMPLE 4

Tests were conducted in the same manner as in Example 1 except that theamount of the DBP solution containing 32% by weight of the TDI polymerblocked with nonyl phenol, was changed to 5 parts by weight and 15 partsby weight, respectively to examine the peel strength due to thedifference in the NCO content. The results are shown in Table 2.

At the same time, a test was conducted in the same manner as in Example1 except that 10 parts by weight of a DBP solution containing 32% byweight of TDI having an average molecular weight of 614 and blocked withnonyl phenol (effective NCO content: 4.4 wt.%) was used, to examine thepeel strength, etc. due to the difference in the average molecularweight of the adhesion-imparting agent. The results are also shown inTable 2.

                                      TABLE 2                                     __________________________________________________________________________                                Comparative                                                 Example 2                                                                              Example 3                                                                              Example 4                                         __________________________________________________________________________    Effective NCO                                                                           0.07     0.21     0.25                                              content (wt. %) in                                                            the plastisol                                                                 Plastisol viscosity                                                           (cps)                                                                         Initial   3,600    4,400    2,800                                             7 days later                                                                            5,600    5,600    3,200                                             Heating temperature                                                                     160                                                                              175                                                                              190                                                                              160                                                                              175                                                                              190                                                                              160                                                                              175                                                                              190                                         (°C.) of the laminate                                                  product                                                                       Peel strength                                                                           2.2                                                                              3.5                                                                              5.5                                                                              3.5                                                                              6.5                                                                              8.7                                                                              2.0                                                                              2.4                                                                              2.7                                         Air bubbles              Δ                                              __________________________________________________________________________

From the above results, it is evident that in order to maintain adequatepeel strength, the adhesion-imparting agent is required to have arelatively high molecular weight at a level of an average molecularweight of at least 1000 and the effective NCO content in the plastisolis required to be at least 0.07% by weight. In Example 3, the heatingrate under the heating condition of 190° C. was rapid, whereby a certainamount of air bubbles appeared.

EXAMPLES 4 to 8

Tests were conducted in the same manner as in Example 1 except thatvarious paste resins having different alkali-metal contents were used.The results are shown in Table 3 together with the results in Example 1.

                                      TABLE 3                                     __________________________________________________________________________                  Examples                                                                      4   5   6   7*  1   8                                           __________________________________________________________________________    Alkali metal content (ppm)                                                                  30>    45                                                                               220                                                                               600                                                                               770                                                                              1,000                                      relative to the resin                                                         Plastisol viscosity (cps)                                                     Initial        9,000                                                                             9,000                                                                            3,520                                                                             49,200                                                                            4,000                                                                              7,000                                      7 days later  13,200                                                                            23,040                                                                            5,000                                                                             58,060                                                                            4,800                                                                             12,180                                      175° C. heating, peel strength                                                       3.5 4.0 4.5 4.5 5.5 3.0                                         (kg/inch)                                                                     Formation of air bubbles  Δ Δ                                     Coloring                          Δ                                     __________________________________________________________________________     *A vinyl acetatecontaining copolymer was used.                           

It is evident that the adhesion strength (peel strength) improves almostin proportion to the alkali metal content. However, if the alkali metalcontent exceeds 1000 ppm, the adhesion strength decreases, and it isevident that a resin containing an alkali metal within a range of from45 to 770 ppm is preferred.

EXAMPLES 9 and 10 and COMPARATIVE EXAMPLES 5 and 6

Tests were conducted in the same manner as in Example 1 except that thepaste resins used in Examples 1 and 4 (alkali metal content: 770 ppm andless than 30 ppm) were used as the vinyl chloride polymer, and theoperation after the addition of the DBP solution of theadhesion-imparting agent during the preparation of the plastisols wasconducted under a relative humidity of 80%. The plastisol viscosity, thepeel strength and the formation of air bubbles were examined in the samemanner as in Example 1, and the results are shown in Table 4. For thepurpose of comparison, a test was conducted in the same manner withrespect to the adhesion-imparting agent used in Comparative Example 2(non-blocked TDI polymer), and the results are also shown in Table 4.

                                      TABLE 4                                     __________________________________________________________________________                       Comparative  Comparative                                                Example 9                                                                           Example 5                                                                            Example 10                                                                          Example 6                                     __________________________________________________________________________    Alkali metal content in the                                                                770 ppm      30 ppm>                                             paste resin                                                                   Adhesion-imparting agent                                                                   Blocked                                                                             Non-blocked                                                                          Blocked                                                                             Non-blocked                                   Effective NCO content                                                                      0.14  0.22   0.14  0.22                                          (wt. % in the sol                                                             Plastisol viscosity (cps)                                                     Initial      3,000 269,300                                                                              7,400  5,000                                        1 day later  3,420 Gel and                                                                              7,800 108,000                                                          solidified                                                 6 days       3,440        9,400 Gel and                                                                       solidified                                    Peel strength (kg/inch)                                                                    4.7   2.8    3.4   6.1                                           170° C. × 5 minutes                                              Formation of air bubbles                                                                   Δ                                                                             X                                                          __________________________________________________________________________

In the tests under a relative humidity of 80%, the plastisol viscositystability was good in Examples 9 and 10, whereas in ComparativeExamples, the plastisols underwent solidification as time passed,whereby the plastisol viscosity stability was too poor to be practicallyuseful. In Example 9 where the alkali metal content was high, the peelstrength was even higher than that in Example 10 probably because thedissociation of the blocked polymer was thereby facilitated. However,the absorption of moisture tends to increase, thus leading to theformation of air bubbles. In Comparative Example 5, the effective NCOcontent decreased due to the absorption of moisture, whereby the peelstrength became extremely poor. Thus, the peel strength varies dependingupon the alkali metal content. From the results of various tests, themost appropriate amount is within a range of from 200 to 800 ppm.

EXAMPLES 11 to 15

Tests were conducted in the same manner as in Example 1 except that thepaste resins having alkali metal contents of 770 ppm and 220 ppm as usedin Examples 1 and 6, respectively, were used, and the type of thestabilizer and block dissociation-promoting agent was changed to (A)tribasic lead sulfate, (B) dibutyltin mercaptide and (C) a Na-Zn typecomposite stabilizer (alkali metal content relative to the resin: 285ppm). The results are shown in Table 5.

                  TABLE 5                                                         ______________________________________                                                        Example                                                                       11   12     13     14   15                                    ______________________________________                                        Paste resin       Same as used in                                                                            Same as                                                          Example 6    used in                                                                       Example 1                                      Stabilizer        (A)    (B)    (C)  (A)  (B)                                 Total alkali metal content (ppm)                                                                220    220    505  770  770                                 Plastisol viscosity (cps)                                                     Initial           4,480  2,400  3,200                                                                              5,200                                                                              3,600                               7 days later      6,800  3,400  5,600                                                                              7,600                                                                              4,600                               Peel strength (kg/inch) of the                                                                  4.1    4.0    4.3  5.2  4.8                                 laminated product heated at                                                   175° C. for 5 min.                                                     Formation of air bubbles                                                                        Δ                 Δ                             ______________________________________                                    

EXAMPLE 16

    ______________________________________                                        Vinyl chloride polymer (paste resin,                                                                 100 parts by weight                                    alkali metal content: 220 ppm)                                                Plasticizer (di-2-ethylhexyl phthalate                                                                60 parts by weight                                    (DOP))                                                                        Epoxy stabilizer (FEP-13, tradename,                                                                  3 parts by weight                                     manufactured by Adeka Argus K.K.)                                             Ba--Zn type stabilizer and block dissoci-                                                             2 parts by weight                                     ation-promoting agent (AC-303, tradename,                                     manufactured by Adeka Argus K.K.)                                             Dibutyl phthalate (DBP) solution                                                                     Various amounts                                        of adhesion-imparting agent                                                   ______________________________________                                    

The above identified components were left to stand for a few days in aconstant temperature and humidity chamber at a temperature of 23° C.under a relative humidity of 50%, then weighed and mixed in a constanttemperature room in the following manner.

The paste resin, DOP (corresponding to 45 PHR), the stabilizer and blockdissociation-promoting agent, were introduced into a Hobart mixer, anduniformly mixed and kneaded, and then a predetermined amount of adibutyl phthalate (DBP) solution of the adhesion-imparting agent wasadded thereto. Further, DOP was added to bring the amount to 60 parts byweight, and the composition was uniformly mixed, and then vacuumed fordefoaming to obtain a plastisol composition.

The details of the composition, the plastisol viscosity, the peelstrength (adhesive strength to the polyethylene terephthalate wovenfabric), the formation of air bubbles and the coloring, were as shown inTable 6.

                  TABLE 6                                                         ______________________________________                                                          Example 16                                                  ______________________________________                                        Plastisol composition                                                         Adhesion-imparting agent                                                                          TDI isocyanurate polymer                                                      blocked with p-oxybenzoic                                                     acid 2-ethylhexyl ester                                   Average molecular weight                                                                          1,300                                                     Solution concentration (wt. %)                                                                    33                                                        Effective NCO content (wt. %)                                                                     2.52                                                      in the solution                                                               Amount of the solution added                                                                      15                                                        (phr)                                                                         Effective NCO content (wt. %)                                                                     0.21                                                      in the plastisol                                                              Plastisol viscosity (cps)                                                     Initial             3,000                                                      2 days later       4,000                                                      7 days later       4,600                                                     14 days later       6,000                                                     21 days later       7,200                                                     30 days later       8,200                                                     Physical properties of the laminate                                           product                                                                       Heating temperature (°C.)                                                                  160     175      190                                      Peel strength (kg/inch)                                                                           5.6     6.6      7.8                                      Formation of air bubbles                                                      Coloring                             Δ                                  ______________________________________                                    

Whereas in the plastisol composition of the present invention, theplastisol viscosity stability is good, and a remarkable improvement wasobserved in the peel strength even at such a low heating temperature as160° or 175° C., as compared with the composition of Comparative Example2.

EXAMPLES 17 and 18 and COMPARATIVE EXAMPLE 7

Tests were conducted in the same manner as in Example 16 except that theamount of the DBP solution containing 33% by weight of the TDI polymerblocked with p-oxybenzoic acid 2-ethylhexyl ester was changed to 5 partsby weight and 10 parts by weight, to examine the peel strength due tothe difference in the NCO content. The results are shown in Table 7.

At the same time, a test was conducted in the same manner as in Example16 except that 10 parts by weight of a DBP solution containing 33% byweight of TDI having an average molecular weight of 674 and blocked withp-oxybenzoic acid 2-ethylhexyl ester (effective NCO content: 4.2 wt.%),was used, to examine the peel strength due to the difference in theaverage molecular weight of the adhesion-imparting agent. The resultsare shown in Table 7.

                                      TABLE 7                                     __________________________________________________________________________                                Comparative                                                 Example 17                                                                             Example 18                                                                             Example 7                                         __________________________________________________________________________    Effective NCO                                                                           0.07     0.14     0.24                                              content (wt. %) in                                                            the plastisol                                                                 Plastisol viscosity                                                           (cps)                                                                         Initial   2,960    3,000    2,900                                             7 days later                                                                            3,760    4,000    3,800                                             Heating temperature                                                                     160                                                                              175                                                                              190                                                                              160                                                                              175                                                                              190                                                                              160                                                                              175                                                                              190                                         (°C.) of the laminate                                                  product                                                                       Peel strength                                                                            4.2                                                                              4.3                                                                              4.5                                                                              4.5                                                                              5.5                                                                              6.4                                                                              2.2                                                                              2.4                                                                              2.7                                        Air bubbles                                                                   __________________________________________________________________________

From the above results, it is evident that in order to maintain adequatepeel strength, the adhesion-imparting agent is required to have arelatively high molecular weight at a level of an average molecularweight at least 1000, and the effective NCO content in the plastisol isrequired to be at least 0.05% by weight.

EXAMPLES 19 to 21

Tests were conducted in the same manner as in Example 18 except thatpaste resins having different alkali metal contents were used. Theresults are shown in Table 8 together with the results of Example 18.

                  TABLE 8                                                         ______________________________________                                                   Examples                                                                      19     18      20        21                                        ______________________________________                                        Alkali metal content                                                                          45      220     600    770                                    (ppm) relative to the                                                         resin                                                                         Plastisol viscosity                                                           (cps)                                                                         Initial       6,400   3,000    6,000 7,440                                    7 days later 12,200   4,000   21,000 Not                                                                           measurable                                                                    due to                                                                        solidifi-                                                                     cation                                   175° C. heating, peel                                                                  5.4      5.5     5.2 4.9                                      strength (kg/inch)                                                            Formation of air                                                              bubbles                                                                       Coloring                             Δ                                  ______________________________________                                    

As shown by Example 21, when a resin having a high alkali metal contentis employed, a decrease is observed in the plastisol viscosity stabilityand in the peel strength. It is evident that a resin containing analkali metal within a range of from 45 to 600 ppm is preferablyemployed. Further, the composition containing a high alkali metalcontent stays in the state of a plastisol for a period of about fivedays and then solidifies, and such a composition will be required to beused quickly.

EXAMPLES 22 to 25 and COMPARATIVE EXAMPLE 8

The adhesion strength to the polyethylene terephthalate film wasevaluated.

Tests were conducted in the same manner as in Example 16 except that thetype of the stabilizer and block dissociation-promoting agent waschanged. The results are shown in Table 9. The test results of aplastisol wherein no adhesion-imparting agent was added, are also shownin Table 9.

                                      TABLE 9                                     __________________________________________________________________________                    Example                                                                            Example                                                                            Example                                                                            Example                                                                            Example                                                                            Comparative                                          22   23   16   24   25   Example 8                            __________________________________________________________________________    Paste resin     Same as used in Example 16                                    Stabilizer      A    B    C    D    E    C                                    Total alkali metal content (ppm)                                                                220                                                                                220                                                                                220                                                                                220                                                                                600                                                                                220                                Plastisol viscosity (cps)                                                     Initial         3,600                                                                              2,800                                                                              3,000                                                                              7,840                                                                              5,120                                                                              3,360                                7 days later    5,800                                                                              4,400                                                                              4,600                                                                              14,400                                                                             400,000                                                                            5,000                                Peel strength (kg/inch)                                                                       1.0  0.8  0.5  0.4  0.8  0.1                                  160° C. × 5 minutes                                              Formation of air bubbles                                                      __________________________________________________________________________     Stabilizer:                                                                   (A) Tribasic lead sulfate                                                     (B) Dibutylrin mercaptide                                                     (C) Ba--Zn type stabilizer                                                    (D) Ca--Zn type stabilizer                                                    (E) Na--Zn type stabilizer (alkali metal content relative to the resin:       380 ppm)                                                                 

Compositions according to the present invention show excellent adhesionalso to the polyester-type film.

As shown by Examples 22 and 23, lead type and tin type stabilizers arepreferred as the stabilizer and block dissociation-promoting agent,since they serve to improve the adhesion strength in a low temperaturelamination.

EXAMPLE 26 and COMPARATIVE EXAMPLE 9

By using a plastisol composition according to the present invention, theproperties for application to an automobile undercoating and sealant,were evaluated. The blend for evaluation was as shown below, and theresults of a plastisol in which the adhesion imparting agent used inExample 16 was added and a plastisol in which no such an agent wasadded, are shown in Table 10.

    ______________________________________                                        Vinyl chloride paste resin                                                                          40 parts by weight                                      (Homo-Poly, manufactured by                                                   Mitsubishi Kasei Vinyl Company                                                average degree of polymerization                                              .sup.-- P=1500)                                                               Vinyl chloride paste resin (Co-                                                                     40 parts by weight                                      Poly, manufactured by Mitsubishi                                              Kasei Vinyl Company average degree                                            of polymerization .sup.-- P=1350)                                             Vinyl chloride blending resin                                                                       20 parts by weight                                      (manufactured by Mitsubishi                                                   Kasei Vinyl Company average degree                                            of polymerization .sup.-- P=1,000)                                            DOP (plasticizer)     120 parts by weight                                     Calcium carbonate     200 parts by weight                                     (ground type,                                                                 average particle size                                                         -- D=5 μm                                                                  Tribasic lead sulfate 1 part by weight                                        Ba--Zn type stabilizer                                                                               2 parts by weight                                      (AC303, tradename)                                                            DBP solution of the adhesion-                                                                       15 parts by weight                                      imparting agent                                                               ______________________________________                                    

The plastisol was prepared by mixing and kneading in the same manner asin Example 16, then adding the adhesion-imparting agent, and adding theplasticizer to bring the total content of the plasticizer to apredetermined level.

The plastisol was coated on a plate having an undercoating formed bycationic electrodeposition, in a thickness of 0.5 mm. Separately, a pairof undercoated electrodeposited plates were laminated with a coatinglayer of the plastisol composition having a thickness of 0.5 mminterposed therebetween in the form of a sandwiched structure. Thecoated plate and the laminate of the sandwiched structure wererespectively heated at 130° C. for 30 minutes in an oven to obtainshaped products. With respect to the former, the 90° peel strength(pulling speed: 50 mm/min) was obtained, and with respect to the latter,the shearing peel strength (pulling speed: 5 mm/min) was obtained.

Further, with respect to the viscosity stability, the plastisol was leftto stand at 40° C. for 72 hours, and the viscosity at 5 rpm wasmeasured.

                  TABLE 10                                                        ______________________________________                                                                  Comparative                                                          Example 26                                                                             Example 9                                           ______________________________________                                        Plastisol composition                                                         Amount of the solution                                                                           15         0                                               Effective NCO content (wt. %)                                                                    0.09       0                                               in the plastisol                                                              Peel strength                                                                 Shearing* (kg/cm.sup.2)                                                                          16         6                                               90° (kg/inch)                                                                             1.8        0.02                                            Plastisol viscosity (cps)                                                     Initial             10,000    30,000                                          72 hours later     100,000    60,000                                          ______________________________________                                         *Measuring method: JIS K 6830 (Method for testing an automobile sealing       material)                                                                

It is evident that the plastisol composition according to the presentinvention has excellent adhesion strength to the cationicelectrodeposition coated plate.

In the following Examples, the methods for the evaluation of theundercoating materials are as follows.

(1) Tests for the viscosity and the storage stability of theundercoating materials (plastisol compositions)

The plastisol viscosity at 5 rpm was measured at a plastisol temperatureof 40°±1° C. by using B8H Model viscometer #7 rotor, manufactured byTokyo Keiki K. K.

The storage stability was determined in such a manner that a glasscontainer containing the plastisol composition was immersed in aconstant temperature water tank at a temperature of 40°±1° C., after apredetermined number of days, the composition was stirred gently for oneminute by a stirring rod two hours before the measurement of theviscosity, and the plastisol viscosity was measured as mentioned above.

(2) Test for shearing peel strength

The shearing adhesion strength was measured in accordance with JIS K6830 (method for testing an automobile sealing material) by using acationic electrodeposition coated plate with a coating layer as a testpiece. The test was conducted with a plastisol layer thickness of 0.5 mmwith heat treatment at a temperature of from 120° to 140° C. for 30minutes under a pulling speed of 5 mm/min.

(3) Test for water resistance

The same test piece as used for the test for measuring the shearing peelstrength in above item (2) was immersed in warm water at 40° C. for 7days, and then dried in air for 1 day. Then, the shearing adhesionstrength was measured in the same manner as in the above item (2) todetermine the water resistance.

(4) Evaluation of coloring

The coloring and the outer appearance of the vinyl chloride polymerlayer in the coating after the shearing peel strength test in the aboveitem (2), were examined by visual observation, and evaluated inaccordance with the following standards.

∘: No coloring

Δ: Some coloring

χ: Substantial coloring

EXAMPLES 27 to 30 and COMPARATIVE EXAMPLES 10 and 11

    ______________________________________                                        Vinyl chloride polymer (paste resin)                                                                80 parts by weight                                      Blending resin        20 parts by weight                                      Plasticizer (DOP)     120 parts by weight                                     Filler (CaCO.sub.3, -- D=5 μm)                                                                   200 parts by weight                                     Stabilizer and block   3 parts by weight                                      dissociation-promoting agent                                                  Solution of the adhesion-                                                                           15 parts by weight                                      imparting agent                                                               ______________________________________                                    

The above-identified components were left to stand in a constanttemperature and humidity chamber at 23° C. under a relative humidity of50% for a few days, then weighed and mixed in a constant temperatureroom in the following manner.

The paste resin, the blending resin, DOP, the filler and the stabilizerand block dissociation-promoting agent were introduced into a Hobartmixer, and uniformly mixed. Then, the solution of the adhesion-impartingagent was added, and the mixture was again uniformly mixed. Then, themixture was vacuumed for defoaming to obtain a plastisol composition asan undercoating material. The detailed composition of the undercoatingmaterial, the plastisol viscosity, the shearing peel strength, thecoloring state, etc. are shown in Table 11.

For the purpose of comparison, tests were conducted in the same manneras in the above Example with respect to the composition wherein noadhesion-imparting agent was added and the composition wherein acommercially available adhesion-imparting agent was added. The resultsare also shown in Table 11.

                                      TABLE 11                                    __________________________________________________________________________                    Example                   Comparative Example                                 27     28 29  30          10    11                            __________________________________________________________________________    Paste resin     Average degree                                                                              .sup.--P 1400, Vinyl chloride-                                                            .sup.--P 1500                                       of polymerization                                                                           vinyl acetate copolymer                                                                   Vinyl chloride                                      (.sup.-- P) 1500                                                                            (vinyl acetate content:                                                                   homopolymer                                         Vinyl chloride homopolymer                                                                  4 wt. %)                                        Blending resin  .sup.-- P 1000 Average particle size: 35 μm                                Vinyl chloride-vinyl acetate copolymer (vinyl acetate                         content: 3 wt. %)                                             Solution of the adhesion-                                                                     A         B               None  C                             imparting agent*                                                              Stabilizer and block                                                                          Ba--Zn type                                                                          Tribasic lead sulfate                                  dissociation-promoting agent                                                                  stabilizer                                                    Plastisol viscosity (poise)                                                                   154    200                                                                              188 208         200   105                           Storage stability (poise)                                                     1 day later     174    230                                                                              214 309         220   108                           3 days later    184    257                                                                              241 774         240   120                           Shearing peel strength (kg/cm.sup.2)                                          Heating            7.5  15                                                                                17.7                                                                             18            4.5                                                                                12.2                        130° C. × 30 min                                                 Peeling         Cohesive failure          Interfacial                                                                         Cohesive                                                                peeling                                                                             failure                       Coloring                                        X                                                                             (yellowing)                   __________________________________________________________________________     *A: DBP solution containing 33% by weight of a TDI isocyanurate polymer       blocked with poxybenzoic acid2-ethylhexyl ester (average molecular weight     .sup.--MW 1300), effective NCO: 2.52 wt. %.                                   B: A DBP solution containing 32% by weight of a TDI polymer blocked with      nonyl phenol (average molecular weight .sup.--MW 1182), effective NCO:        2.54 wt. %.                                                                   C: A polyaminoamide type Eurutek 506 (manufactured by Schelling Co.).    

Cohesive failure was observed in all cases of the peeling states inExamples 27 to 30 wherein undercoating materials of the presentinvention were used, thus indicating excellent adhesion properties. Theshearing peel strength value remarkably improves by the use of a leadtype stabilizer. The viscosity stability is good in the case of acombination of a paste resin of the homopolymer and a blending resin ofthe copolymer.

A further feature of the present invention is that as compared with thecommercial product in Comparative Example 11, no substantial thermalcoloring is observed after the heat treatment for lamination.

EXAMPLES 31 and 32

Tests were conducted in the same manner as in Example 27 except that thecomposition of the vinyl chloride polymer i.e. the paste resin and theblending resin was changed. The results are shown in Table 12 togetherwith the result of Example 27.

                  TABLE 12                                                        ______________________________________                                                    Example                                                                       27     31         32                                              ______________________________________                                        Paste resin        Same as    Same as                                                            used in    used in                                                            Example 30 Example 27                                      Blending resin     .sup.-- P 1000 Average                                                        particle size: 40 μm                                                       Vinyl chloride                                                                homopolymer                                                Solution of the    A          A                                               adhesion-imparting                                                            agent                                                                         Stabilizer and block                                                                             Ba--Zn type stabilizer                                     dissociation-promot-                                                                             (AC-303, manufactured                                      ing agent          by Adeka Argus K.K.)                                       Plastisol viscosity                                                                         154      200        116                                         (poise)                                                                       Storage stability                                                             (poise)                                                                       1 day later   174      401        119                                         3 days later  184      765        123                                         Shearing peel                                                                 strength (kg/cm.sup.2)                                                        Heat treatment                                                                120° C. × 30 min                                                               7.4      8.3        3.9                                         130° C. × 30 min                                                               7.5      8.3        5.7                                         140° C. × 30 min                                                               8.2      8.3        7.9                                         Coloring                                                                      ______________________________________                                    

Examples 27, 31 and 32 show the low temperature melting properties andthe low temperature adhesive properties according to the presentinvention.

According to the present invention, a uniform cohesive failure state isobserved at the peeled surface even under a low temperature laminationcondition at 120° C. for 30 minutes. It is seen that among them, theabove-mentioned resin blend of Example 27 is preferred as a combinationof resins which provides good physical properties such as shearing peelstrength as well as excellent viscosity stability.

EXAMPLES 33 to 38

    ______________________________________                                        Paste resin (same as used in                                                                      80 parts by weight                                        Example 27)                                                                   Blending resin (same as used in                                                                   20 parts by weight                                        Example 27)                                                                   Butylbenzyl phthalate (BBP)                                                                      130 parts by weight                                        CaCO.sub.3 (average particle                                                                     200 parts by weight                                        size .sup.-- D = 5 μm)                                                     Tribasic lead sulfate                                                                             5 parts by weight                                         Solution of adhesion-                                                                            Prescribed amount                                          imparting agent                                                               ______________________________________                                    

With the above composition wherein the type and amount of theadhesion-imparting agent were varied, the evaluation was carried out inthe same manner as in Examples 27 to 30. The results are shown in Table13.

                                      TABLE 13                                    __________________________________________________________________________                     Example                                                                       33   34   35  36   37   38                                   __________________________________________________________________________    Solution of the adhesion-                                                                      A    A    A   B    B    B                                    imparting agent                                                               Amount of the solution added (phr)                                                             10   15   20  10   15   20                                   Amount of the block added (phr)                                                                3.3  5.0  6.6 3.2  4.8  6.4                                  Plastisol solution (poise) Initial                                                             1048 880  720 1656 1352 1088                                 Storage stability (poise)                                                     3 days later     1136 1016 864 1696 1376 1120                                 7 days later     1352 1120 992 1736 1392 1152                                 Shearing peel strength (kg/cm.sup.2)                                          Heat treatment 120° C. × 30 min                                                   13   17   19  13   12   12                                   Peeling          Inter-                                                                             Cohesive failure                                                                       Inter-                                                                             Cohesive failure                                           facial        facial                                                          peeling       peeling                                        Coloring                                                                      __________________________________________________________________________

As shown by Examples 34 and 37, in each of the adhesion-imparting agentsA and B, adequate adhesive properties to the cation electrodepositioncoated plate can be obtained if the blocked diisocyanate polymercomponent is added in an amount of about 5 parts by weight and at least1% of the entire plastisol.

EXAMPLES 39 and 40 and COMPARATIVE EXAMPLE 12

    ______________________________________                                        Paste resin (VINIKA P-540,                                                                         80 parts by weight                                       manufactured by Mitsubishi Chemical                                           Industries Co., Ltd.)                                                         Blending resin (3% copolymer)                                                                      20 parts by weight                                       (same as used in Example 27)                                                  Polyester type plasticizer                                                                         100 parts by weight                                      (--MW = 1200)                                                                 B.B.P.               20 parts by weight                                       Tribasic lead sulfate                                                                               3 parts by weight                                       CaCO.sub.3 (.sup.-- D = 5 μm)                                                                   200 parts by weight                                      Adhesion-imparting agent                                                                            5 parts by weight                                                            (effective amount)                                       Diluent (mineral spirit)                                                                           10 parts by weight                                       ______________________________________                                    

With the above composition wherein A, B or C was used as theadhesion-imparting agent, the evaluation was carried out. The diluentwas added later and mixed. The results are shown in Table 14.

                  TABLE 14                                                        ______________________________________                                                                     Comparative                                                Example 39                                                                             Example 40                                                                              Example 12                                       ______________________________________                                        Adhesion-imparting                                                                        A          B         C                                            agent                                                                         Plastisol viscosity                                                                       200        96        424                                          (poise) Initial                                                               Storage stability                                                             (poise)                                                                       2 days later                                                                              240        97        432                                          3 days later                                                                              260        98        466                                          Shearing peel                                                                 strength (kg/cm.sup.2)                                                        Heat treatment                                                                            11.0       11.0      10.0                                         120° C. × 30 min                                                 Peeling     Cohesive failure Interfacial                                                                   peeling                                          Water resistance                                                                          10.0       10.3      5.5                                          (kg/cm.sup.2)                                                                 Peeling     Cohesive failure Interfacial                                                                   peeling                                          ______________________________________                                    

In the case of the adhesion-imparting agents A and B according to thepresent invention, the deterioration in the adhesive properties oradhesion after the hot water dipping treatment is small, thus indicatingthat the water resistance is improved remarkably as compared with C ofthe Comparative Example 12.

EXAMPLES 41 to 44

Tests were conducted in the same manner as in Example 40 except that inthe composition in Example 40, a half (40 phr) of 80 phr of the pasteresin VINIKA P-540 was substituted by the following paste resins, andthe amount of the diluent was reduced to 8 phr, and various propertieswere measured. The results are shown in Table 15.

                                      TABLE 15                                    __________________________________________________________________________             Example                                                                       41  42      43      44                                               __________________________________________________________________________    Paste resin used                                                                       --  .sup.-- P = 1200                                                                      VINIKA P 100                                                                          VINIKA P 500                                     in combination                                                                             Vinyl chloride                                                                        (.sup.-- P 1400, vinyl                                                                (.sup.-- P 1400, vinyl                                        homopolymer                                                                           chloride-2-                                                                           chloride-vinyl                                                        hydroxypropyl                                                                         acetate copolymer,                                                    acrylate                                                                              vinyl acetate                                                         copolymer)                                                                            content: 4 wt. %)                                Initial plastisol                                                                      310 240     328     352                                              viscosity (poise)                                                             Storage stability                                                             (poise)                                                                       2 days later                                                                           313 247     328     493                                              6 days later                                                                           320 256     328     1160                                             Shearing peel                                                                 strength (kg/cm.sup.2)                                                        Heat treatment                                                                         11.0                                                                              9.5     12.0    14.0                                             120° C. × 30 min                                                 Peeling  Cohesive failure                                                     Coloring                                                                      __________________________________________________________________________

As the vinyl chloride polymer of the present invention, varioushomopolymers and copolymers may be used alone or in combination as amixture.

I claim:
 1. A plastisol composition, comprising:a vinyl chloridepolymer, a plasticizer and an adhesion imparting agent of an aromaticdiisocyanate polymer containing isocyanurate rings blocked with analkylphenol whose alkyl group contains at least 4 carbon atoms.
 2. Theplastisol composition according to claim 1, wherein the aromaticdiisocyanate is tolylene diisocyanate or diphenylmethane diisocyanate.3. The plastisol composition according to claim 1, wherein theadhesion-imparting agent has an effective isocyanate content of from0.03 to 1% by weight based on the total weight of the plastisolcomposition.
 4. The plastisol composition according to claim 1, whereinsaid plasticizer is a phthalate plasticizer, a fatty acid esterplasticizer, a phosphate plasticizer, or an epoxy plasticizer.
 5. Theplastisol composition according to claim 1, wherein said plasticizer ispresent in said composition in an amount ranging from 30-600 parts byweight relative to 100 parts by weight of the vinyl chloride resin. 6.An undercoating material composed of a plastisol composition comprisinga vinyl chloride polymer and a plasticizer as main components, andfurther containing an aromatic diisocyanate polymer blocked with analkylphenol whose alkyl group contains at least 4 carbon atoms as anadhesion-imparting agent.
 7. The undercoating material according toclaim 6, wherein the diisocyanate polymer contains isocyanurate rings.